Enhancement of ionic conductivity of PEO based polymer electrolyte by the addition of nanosize ceramic powders

The ionic conductivity of polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) has been improved by the addition of nanosize ceramic powders (TiO2 and AL2O3). The PEO based solid polymer electrolytes were prepared by the solution-casting method. Electrochemical measurement shows that the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte has the best ionic conductivity (about 10(-4) S cm(-1) at 40-60 degrees C). The lithium transference number of the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte was measured to be 0.47, which is much higher than that of bare PEO polymer electrolyte. Ac impedance testing shows that the interface resistance of ceramic-added PEO polymer electrolyte is stable. Linear sweep voltammetry measurement shows that the PEO polymer electrolytes are electrochemically stable in the voltage range of 2.0-5.0 V versus a Li/Li+ reference electrode.     

水铝英石/PEO/LiClO4复合固态聚合物电解质中组分相互作用对PEO结晶的影响

为解决现有锂离子电池的安全性问题,固态电解质的研究备受关注。以Na2SiO3和AlCl3·6H2O为原料,采用溶胶-凝胶法制备出水铝英石(AL);通过溶液共混法将其与聚环氧乙烷/高氯酸锂(PEO/LiClO4)复合得到复合固态聚合物电解质。利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、差示扫描量热分析仪(DSC)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)以及光学显微镜(OM)对样品进行结构分析及形貌表征。结果表明:水铝英石和LiClO4与PEO间的非价键力相互作用(络合、氢键及Lewis酸-碱作用)显著抑制PEO的结晶。随着水铝英石含量的增加,PEO的结晶度呈现出先降低后增加的趋势;而随着锂盐含量的增加,PEO的结晶度持续降低,当EO/Li+摩尔比为10∶1,水铝英石的含量为5%(质量分数)时,复合固态聚合物电解质的结晶度最低,仅为4.12%。     

Influence of 1-ethyl-3-methylimidazolium bis (trifluoromethyl sulfonyl) imide plasticization on zinc-ion conducting PEO/PVdF blend gel polymer electrolyte

The influence in terms of plasticizer on zinc-ion conducting polymer blend electrolyte system, [PEO (90 wt%)/PVdF (10 wt%)]-15 wt% Zn (CF₃SO₃)₂] with various concentrations of 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (EMIMTFSI) was investigated. The freshly-prepared thin films of [PEO (90 wt%)/PVdF (10 wt%)]-15 wt% Zn (CF₃SO₃)₂)?+?x wt% EMIMTFSI, where x?=?1, 3, 5, 7, and 10 wt%] were characterized by means of X-ray diffraction (XRD), Fourier transformed infrared (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and impedance analysis techniques. The room temperature XRD patterns tend to support the enhanced amorphous phase as a result of deducing the degree of crystallinity of the polymer blend–salt system by the addition of 7 wt% EMIMTFSI. The relevant SEM images of 7 wt% EMIMTFSI incorporated gel polymer electrolyte exhibit a minimised spheurilite structure when compared to that of the polymer blend–salt system. Unusually, the highest ionic conductivity realized in the case of the typical gel polymer electrolyte system, [PEO/PVdF-Zn (CF₃SO₃)₂ + 7 wt% EMIMTFSI] is found to be 1.63?×?10^?4 S cm^?1 at room temperature. The temperature dependence of conductivity has been examined based on the Vogel–Tammann–Fulcher (VTF) equation, thereby suggesting the segmental chain motion and free volume changes. The occurrence of ion dynamics and dielectric relaxation behaviour in the chosen system has been analysed in a detailed fashion at room temperature using frequency response impedance formalisms involving electric modulus and dielectric permittivity features.     

Conductivity study of polyethylene oxide (PEO) complexed with sodium bicarbonate

Ion conducting thin film polymer electrolytes based on polyethylene oxide (PEO) complexed with NaHCO₃ salt has been prepared using solution-cast technique. The complexation of NaHCO₃ salt with PEO is confirmed by XRD and IR studies. DC conductivity in the temperature range 303–368 K has been evaluated. The conductivity is found to increase in the PEO complex with the NaHCO₃ salt and also with an increase in temperature. Using this polymer electrolyte, an electrochemical cell with the configuration Na/(PEO + NaHCO₃)/(I₂ + C + electrolyte) has been fabricated and its discharge characteristics studied. Open Circuit Voltage (OCV) and Short Circuit Current (SCC) are found to be 2.69 V and 1.28 mA, respectively. Other parameters associated with the cell are evaluated and presented in this paper.     

Effect of ZnO nanoparticles on the structure and ionic relaxation of poly(ethylene oxide)-LiI polymer electrolyte nanocomposites

The effect of ZnO nanoparticles on the structure and ionic relaxation of LiI salt doped poly(ethylene oxide) (PEO) polymer electrolytes has been investigated. X-ray diffraction, high resolution transmission electron microscopy and field emission scanning electron microscopy show that ZnO nanoparticles dispersed in the PEO-LiI polymer electrolyte reduce the crystallinity of PEO and increase relative smoothness of the surface morphology of the nanocomposite electrolyte. The electrical conductivity of the nanocomposites is found to increase due to incorporation of ZnO nanoparticles. We have shown that the structural modification due to insertion of ZnO nanoparticles results in the enhancement of the mobility i.e., the hopping rate of mobile Li+ ions and hence the ionic conductivity of PEO-LiI-ZnO nanocomposite electrolyte.     

一种含硫聚合物电解质的合成及性能

针对聚氧化乙烯基固态聚合物电解质存在的问题,分别以PEG400、PEG600合成了相应的1,3-二氯-2-丙醇聚乙二醇醚,并通过在Na2S2溶液中聚合,制备了1,3-二氯-2-丙醇聚乙二醇醚基聚硫化合物{PS(DCP-PEG)}。通过红外光谱(IR)、元素分析、交流阻抗、差示扫描量热(DSC)、热重分析(TG)等测试对该聚合物的结构、热力学以及导电性能进行表征。结果表明,合成的产物结构与设计的结果一致.该含硫聚合物电解质力学性能优良,电极接触好,热分解温度在220℃以上,室温电导率可达10-5S/cm,在锂硫聚合物电池中具有实际应用价值。     

Influence of Finely Dispersed Carbon Nanotubes on the Performance Characteristics of Polymer Electrolytes for Lithium Batteries

Electrospun membranes of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)/multiwall carbon nanotube (MWCNT) composite are prepared and loaded with lithium salts from electrolyte solution. Field emission transmission electron microscopy provides evidence for the uniform distribution of MWCNTs into the matrix of PVdF-HFP. The interconnected morphology as evident from field emission scanning electron micrograph forms the path for the lithium ion conduction. Results from electrochemical impedance spectroscopy inform that the presence of MWCNTs in PVdF-HFP matrix improves interfacial stability between lithium electrode and membrane and augment conduction path in the polymer electrolyte membrane. Further results from impedance measurement reveal the contribution of MWCNTs toward conductivity. A prototype cell is fabricated with PVdF-HFP/MWCNT as polymer electrolyte. The electrospun PVdF-HFP electrolyte membrane with 2% MWCNTs content shows an ionic conductivity of about 5.85 mSmiddotcm^-1 at 25 degC. Also, PVdF-HFP/MWCNT electrolyte membrane exhibits good electrochemical and interfacial stability and can be potentially suitable as electrolyte in lithium ion secondary battery     

Excellent dispersion of MWCNTs in PEO polymer achieved through a simple and potentially cost-effective evaporation casting

A simple, reliable and potentially cost-effective composite film casting procedure is presented using the evaporation of solvent (water) from a dilute mixture of multiwalled carbon nanotubes (MWCNTs) and polyethylene oxide (PEO) polymer. It is found that the fabrication method develops excellent dispersion of MWCNTs in PEO confirmed by morphology observations, final crystallinity of polymer (amorphous) and a lower percolation threshold (closer to theoretical value) as well as higher electrical conductivity. A film thickness prediction model is derived based upon the fact that final film thickness is mainly dependent upon the dimensions of the casting mold and the loading of the MWCNTs and polymer. This simple model provides important insight that the material loss and the actual density of the base polymer are critical factors making the current casting method truly cost effective and controlling final thickness.     

Performance characteristics of guanine incorporated PVDF-HFP/PEO polymer blend electrolytes with binary iodide salts for dye-sensitized solar cells

In this work, we have investigated the influence of guanine as an organic dopant in dye-sensitized solar cell (DSSC) based on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) polymer blend electrolyte along with binary iodide salts (potassium iodide (KI) and tetrabutylammonium iodide (TBAI)) and iodine (I₂). The PVDF-HFP/KI + TBAI/I₂, PVDF-HFP/PEO/KI + TBAI/I₂ and guanine incorporated PVDF-HFP/PEO/KI + TBAI/I₂ electrolytes were prepared by solution casting technique using DMF as solvent. The PVDF-HFP/KI + TBAI/I₂ electrolyte showed an ionic conductivity value of 9.99 × 10⁻⁵ Scm⁻¹, whereas, it was found to be increased to 4.53 × 10⁻⁵ Scm⁻¹ when PEO was blended with PVDF-HFP/KI + TBAI/I₂ electrolyte. However, a maximum ionic conductivity value of 3.67 × 10⁻⁴ Scm⁻¹ was obtained for guanine incorporated PVDF-HFP/PEO/KI + TBAI/I₂ blend electrolyte. The photovoltaic properties of all these polymer electrolytes in DSSCs were characterized. As a consequence, the power conversion efficiency of the guanine incorporated PVDF-HFP/PEO/KI + TBAI/I₂ electrolyte based DSSC was significantly improved to 4.98% compared with PVDF-HFP/PEO/KI + TBAI/I₂ electrolyte based DSSC (2.46%). These results revealed that the guanine can be an effective organic dopant to enhance the performance of DSSCs.     

PEO:KIO3 Polymer electrolyte system- its application to solid state electrochemical cell

In search of polymer electrolyte based on PEO- salt complexes other than the extensively studied lithium-based polymer electrolytes, we report the new polymer electrolyte based on PEO complexed with KIO₃ salt. Several experimental techniques such as differential scanning calorimetry (DSC), composition dependence conductivity, temperature dependence conductivity and transport number measurements have been performed to characterize the polymer electrolyte. DSC study reveals that the melting temperature of pure PEO is shifting towards lower temperatures by complexing with the KIO₃ salt. The conductivity-temperature plots show two regions below and above the melting point (T_m). Transport numbers data suggest that the charge transport in this polymer electrolyte system is mainly due to ions. Using the polymer electrolyte films solid-state electrochemical cells have been fabricated and the discharge characteristics studied. The open circuit voltage (OCV) and short circuit current (SCC) are found to be 2.69 V and 346µA respectively.     

Electrochemical properties of composite electrolytes based on poly(ethylene oxide)/poly(ethylene imine) containing the inorganic silica fillers

In this study, poly(ethylene oxide) (PEO) and poly(ethylene imine) (PEI) polymer blends containing inorganic silica fillers were studied in order to enhance the ion conductivity and interfacial properties. Lithium perchlorate (LiCIO4) as a salt, and silica (SiO2) as the inorganic filler were introduced in the polymer electrolyte composites and were examined to evaluate their use to improve the ionic conductivity. The addition of inorganic fillers in polymer electrolytes has resulted in high ionic conductivity at a room temperature. The structure and morphology of the solid polymer electrolytes were evaluated using X-ray diffraction (XRD) and scanning electron microscope (SEM). The ionic conductivity was measured by an AC impedance method. The enhanced conductivity was dependent on the decreased crystallinity and more heterogeneous morphologies.     

一种用于染料敏化太阳能电池的插层磷酸锆复合凝胶电解质

介绍了一种新型的应用于染料敏化太阳能电池的插层磷酸锆复合凝胶电解质。磷酸锆通过插层反应使其层间距增大到2.04nm,然后加入到聚氧化乙烯(PEO)凝胶中得到复合凝胶电解质。插层磷酸锆的添加极大地提高了电解质在常温下的离子电导率和离子扩散系数。由该凝胶电解质组装的染料敏化太阳能电池获得了6.61%的光转化效率(AM 1.5G 100mW·cm-2 25℃)。     

Synthesis and characterization of polyethylene oxide based nano composite electrolyte

Polyethylene oxide (PEO) – montmorillonite (MMT) composite electrolytes were synthesised by solution casting technique. The salt used for the study is Lithium perchlorate (LiClO₄). The morphology and percentage of crystallinity data were obtained through X-ray Diffraction and Differential Scanning Caloriemetry. The ionic conductivity of the polymer electrolytes was studied by impedance spectroscopy. The addition of MMT resulted in an increase in conductivity over the temperature range of 25–60^°C. The ionic conductivity of a composite polymer electrolyte containing 1.2 wt% MMT was 1 × 10^?5 S cm^?1 at 25^°C, which is at least one order of magnitude higher than that of the polymer electrolyte (4 × 10^?7S cm^?1). The increase in ionic conductivity is explained on the basis of crystallinity of the polymer electrolyte.     

High concentration exfoliation of graphene in ethyl alcohol using block copolymer surfactant and its influence on properties of epoxy nanocomposites

In this work, high concentration exfoliation (～0.2 mg/ml) of graphene in ethyl alcohol is achieved in presence of block copolymer of polyethylene oxide–polypropylene oxide–polyethylene oxide (PEO–PPO–PEO) using sonication followed by centrifugation. The obtained graphene solution is used to prepare epoxy nanocomposites. Flexural tests were conducted over epoxy nanocomposites. The 0.018 wt% of PEO–PPO–PEO block copolymer exfoliated graphene in epoxy matrix shows 21.7% and 15.8% enhancement in flexural modulus and flexural strength respectively as compared to pure epoxy. Transmission electron microscopy reveals well dispersion of graphene in epoxy matrix; and fractography of flexural fractured sample shows graphene dispersion restricts the crack propagation. The well-dispersed graphene in epoxy matrix increase the dielectric constant and thermal stability of epoxy nanocomposites. Further, the enhanced graphene dispersion in epoxy nanocomposites reduces the glass transition temperature (T_g). Thus, enhanced mechanical properties achieved by dispersion of block copolymer exfoliated graphene in epoxy nanocomposites make it suitable for several applications.     

纳米CeO2对(PEO)10LiClO4电解质体系电学和力学性能的影响

以乙腈为有机溶剂,以高纯纳米稀土氧化物CeO2为无机填料,采用溶液浇铸法制备了(PEO1)0Li-ClO4-x%(质量分数)CeO2(x=0、2、6、9、12、15)全固态复合聚合物电解质(CPE)薄膜。交流阻抗测试表明,适量添加CeO2可有效抑制PEO结晶并拓展锂离子传输所需的无定形区域,从而使CPE薄膜的离子电导率有明显提升,当CeO2的含量为9%(质量分数)时,CPE的离子电导率达到最大值,25℃时为1.71×10-5S/cm,但过量CeO2对锂离子传输具有一定的阻碍,XRD图像证实了这一结论。同时,CeO2的引入可很好地分散和传递应力,对CPE的韧性有明显增强作用,当CeO2的含量为15%(质量分数)时,拉伸强度达到2.07MPa,提高了4.45倍。     

壳聚糖/聚氧乙烯复合纺丝液性能对静电纺丝的影响

为了研究壳聚糖/聚氧乙烯复合纺丝液性能对静电纺丝的影响,利用质量分数为3％的壳聚糖(CS)与聚氧乙烯(PEO)以不同的质量比溶解在浓度为50％的冰乙酸水溶液中制备了CS/PEO复合纺丝液,采用静电纺丝技术制备了CS/PEO复合纳米纤维.用扫描电子显微镜(SEM)对制备出的CS/PEO复合纳米纤维进行表征,并测试了CS/PEO复合纺丝液的溶液性能.从复合纺丝液性能对静电纺纤维成型的影响机理角度对实验结果进行了分析.分析结果表明,在其他静电纺丝参数一定时,纺丝液黏度影响射流的稳定性,从而影响纤维的形貌和直径.只要纺丝液电导率在合适的范围内,对静电纺的影响不大.从泰勒的临界公式中得出了纺丝液临界电压与纺丝液表面张力最佳值的一一对应关系,并与本实验中的实验数据相吻合.     

Optical and electrical properties of indium tin oxide nanofibers prepared by electrospinning

Indium tin oxide (ITO) nanofibers were successfully prepared via an electrospinning method, followed by annealing at 400?°C. Mixed solutions of ITO nanoparticle sol and polyethylene oxide (PEO) were used as precursors of the nanofibers. The PEO decomposed during annealing to yield ITO fibers. The fibers were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), thermo-gravimetric/differential thermal analysis (TG/DTA), UV-vis spectrophotometry and four-probe resistivity measurements. The diameter of the prepared fibers was controlled by adjusting the flow rate and the applied electric current. In(2)O(3) crystallized in the ITO nanofibers with a crystallite size of 27?nm. The optical transmittance in the visible region approached 90% in films deposited for 5?min, confirming that the nanofiber film is still transparent in the optical region. The sheet resistance of the nanofiber film was linearly dependent on the inverse of the deposition time and on the PEO/ITO ratio.     

Structural,electrical and electrochemical parameters of PEO–NaClO3 composite for battery applications

Polyethylene oxide–NaClO₃ composite have been prepared by solution casting technique with different weight percentages as a polymer electrolyte for battery application. The prepared composites were characterized by various tools like XRD, FTIR and SEM. The X-ray diffraction analysis shows the complexation of polymer with salt and existence of both crystalline and amorphous phases. From FTIR spectra confirms the formation of PEO–NaClO₃ composites. SEM images shows the grains are highly agglomerated and its average size increases with increase in salt ratio. Frequency dependence of dielectric property and ac electrical conductivity of polymer electrolytes were studied within the frequency range of 50 Hz to 5 MHz using complex impedance analysis technique. Ionic conductivity follows Arrhenius type behavior as a function of temperature. The fabricated cell of 25 wt.% of PEO–NaClO₃ composites generated high current of 1.79 A.     

Ionic transport in P(VdF-HFP)-PEO based novel microporous polymer electrolytes

A novel microporous polymer electrolyte (MPE) comprising blends of poly(vinylidene fluoride-cohexafluoropropylene) [P(VdF-HFP)] and polyethylene oxide (PEO) was prepared by phase inversion technique. It was observed that addition of PEO improved the pore configuration, such as pore size, pore connectivity and porosity of P(VdF-HFP) based membranes. The room temperature ionic conductivity was significantly enhanced. The highest porosity of about 65% and ionic conductivity of about 7 × 10⁻⁴ S cm⁻¹ was obtained when the weight ratio of PEO was 40%. The liquid electrolyte uptake was found to increase with increase in porosity and pore size. However, at higher weight ratio of PEO (> 40%) porosity, pore size and ionic conductivity was decreased. This descending trend with further increase of PEO weight ratio was attributed to conglomeration effect of PEO at the pores.     

Effect of complexing salt on conductivity of PVC/PEO polymer blend electrolytes

Solid polymer electrolyte membrane comprising poly(vinyl chloride) (PVC), poly(ehylene oxide) (PEO) and different lithium salts (LiClO₄, LiBF₄ and LiCF₃SO₃) were prepared by the solution casting technique. The effect of complexing salt on the ionic conductivity of the PVC/PEO host polymer is discussed. Solid polymer electrolyte films were characterized by X-ray diffraction, FTIR spectroscopy, TG/DTA and ac impedance spectroscopic studies. The conductivity studies of these solid polymer electrolyte (SPE) films are carried out as a function of frequency at various temperatures ranging from 302 K to 353 K. The maximum room temperature ionic conductivity is found to be 0·079 × 10^?4 S cm^?1 for the film containing LiBF₄ as the complexing salt. The temperature dependence of the conductivity of polymer electrolyte films seems to obey the Vogel-Tamman-Fulcher (VTF) relation.